The present disclosure relates generally to a phase shifter, and more specifically, to a wide-bandwidth phase shifter with a true time delay.
Phase shifters are used to change the transmission phase angle of a network. Ideal phase shifters provide low insertion loss, and equal amplitude (or loss) in all phase states. While the loss of a phase shifter is often overcome using an amplifier stage, the less loss, the less power that is needed to overcome it. Most phase shifters are reciprocal networks, meaning that they work effectively on signals passing in either direction.
An RF signal to the phase shifter is split into two signals that are ninety degrees apart, an in-phase (I) signal and a quadrature (Q) signal. The I signal and the Q signal can then be independently modified, with variable gain amplifiers, for example, and then these modified I and Q signals can be recombined to produce an output signal with a modified phase (and possibly gain) relative to the input signal. These devices work well in a narrow frequency range. What is needed, however, is a phase shifter that works well across a broad frequency range.